Electrical – What exactly happens at short circuit

short-circuit

I'm new to electronics and I don't fully understand how short circuiting works. For example I have this battery LiMn 3000mAh, it states:

 Nominal Voltage: 3.6V
 Standard Charge: 2A
 Continuous discharge current: 20A

First thing I don't understand is if I connect a wire between the positive and negative terminal, it would create a short circuit, correct? Can the battery blow up?

My goal is to simply make a hot wire, but I don't understand how will the wire 'determinate' how much current it needs or will it draw full 2A or even 20A from the battery?

If I use resistors, what's their purpose? to protect the battery from all the 'unused' electrons or to protect the wire?

What about taser gun? is it 'short circuiting' and what effect does it have on the power source?

Best Answer

1) Yes, connecting a voltage source directly to its return with a wire creates a short circuit. 1b) Yes, discharging a battery at too high a current draw will overheat the battery and can result in a catastrophic failure (blowing up, boiling electrolyte, fire, other bad things).

2) To just heat a wire, ideally, you would connect it to a controlled (regulated) current source. Then you can adjust the available current to control the heating. Most mid-range and up bench power supplies have a current limit mode.

3) Resistors server many purposes, you will need to be a little less broad. Resistors can limit current, but at the cost of heating up. They won't "Protect" the wire actually, just reduce the current available, and make the resistor a heater.

4) A Taser generates very high voltage pulses, at a very very low current. There is a lot of circuitry between the taser contact points and the battery... Again, really too broad to answer here.

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